1. Field of the Invention
This invention relates generally to controlled flow exhaust manifold systems, and more particularly relates to apparatus for normally sealing a launch tube for rockets or the like from an exhaust duct, and for opening the launch tube in response to gas pressure.
2. Description of the Prior Art
For military applications, rockets, missiles or other exhaust-gas-propelled vehicles are often stored in closely adjacent magazine chambers or launch tubes. In that case, exhaust gas ducts are normally provided to convey rocket exhaust gases generated during rocket ignitions to a safe location. Where available space is at a premium, for example, on ship-board, manifolding of a number of closely adjacent launch tubes or chambers into a common exhaust manifold or plenum chamber is often necessary.
Obvious problems exist if ducts connecting the launch tubes to the common exhaust manifold are normally open, that is, before launch of the vehicles. When one or more of the rockets is intentionally or accidentally ignited, portions of the resulting exhaust gases, which may have a temperature of about 6,000.degree. F., will be circulated through the common manifold and into other launch chambers through the open, connecting ducts. Rockets and rocket warheads in these launch chambers are likely to be ignited or detonated by these hot exhaust gases. At the very least, the hot gases may damage the rockets or associated equipments, such as hold-down devices. Also, if the other launch chambers are open at the upper ends, which is the case of some launch tubes, exhaust gases entering the chambers through connecting ducts escape through the open, outer ends. This in turn may cause extensive heat damage to adjacent installations.
To prevent such occurrences, various types of safety doors or gas valves have been proposed in the past. These are normally installed, either at the outlet opening of each launch chamber or in the connecting duct to the exhaust manifold. When a rocket is accidentally or intentionally ignited, the associated safety door or valve is caused to open, which is usually in response to the exhaust gas. This will admit the exhaust gases into the manifold or exhaust duct. Doors and valves associated with other launch tubes are maintained closed to prevent circulation of the exhaust gases therethrough.
Such doors or valves have been disclosed, for example, in the U.S. Pat. No. to Eastman, 2,445,423, which discloses a safety container for rockets. The patent discloses hold-down doors for each launch tube which consist of a one-way, two-flap check valve. Springs are provided to hold the flaps closed. The rocket blast of an ignited rocket will blow open the check valve.
Another rocket exhaust control apparatus has been disclosed in the applicant's prior U.S. Pat. No. 4,044,648, assigned to the assignee of the present application. This patent discloses flow-control doors which are hinged and provided with counter-weights so that they are normally closed and can open under the pressure of an ignited rocket. The increased pressure in the exhaust duct will maintain the doors closed of other launch chambers of unignited rockets.
Another type of rear door for a rocket launch tube is disclosed in the applicant's copending application Ser. No. 860,039, now U.S. Pat. No. 4,134,327 filed on Dec. 12, 1977, and also assigned to the assignee of the present application. The door is latched open and normally remains open until the rocket is launched. A protective seal or frangible cover may normally close the launch tube until the missile is fired. The door may be released by a sensor as a missile leaves the launch tube. Gases from the launched rocket power the door closed. Subsequently, a latch locks the door in place, thereby to seal off the launch tube from the associated plenum chamber.
The U.S. Pat. No. to Sack, 3,897,962, relates to the nozzle of a gas generator. It is designed to provide a constant gas volume independent of thermodynamic conditions outside the generator. To this end, there is provided an opening in the center of the nozzle, and means to enlarge the opening in response to higher ambient temperatures. Hence, the nozzle is intended for regulating the gas flow, and to hold it at a constant pressure. It is not applicable to a rocket launch tube cover.
Other patents disclose variable thrust nozzles. Among these, for example, is a U.S. Pat. No. to Thielman, 3,079,752. It discloses a variable expansion ratio nozzle intended to increase the efficiency of a nozzle under variable pressures, and to provide more thrust in the upper atmosphere. To this end, a plurality of concentric inner nozzle exit portions are removably secured to an outer nozzle exit portion, thereby to provide variable gas expansion ratios.
Similarly, the U.S. Pat. No. to Steverding, 3,237,402, also relates to a variable thrust nozzle which is enlargeable. It provides optimum thrust in and out of the atmosphere. The exit area of the nozzle is controlled by removable ring-shaped ramps to be ejected at predetermined times. This may, for example, be accomplished by explosive bolts. The U.S. Pat. No. to Gould, 3,309,874, relates to an ablative nozzle which also changes its shape or area. Hence, during flight of the rocket, the nozzle is vaporized or eroded away so that the throat area increases.
Reference is also made to the U.S. Pat. Nos. to Betts et al., 3,968,646, 4,033,121 and 4,036,013. The patents disclose a rocket motor nozzle closure for controlling the release of pressure. The nozzle is arranged to open incrementally or continuously. As a result, the motor pressure is controlled by the rate of change of momentum of the nozzle closure.